After numerous cases of cabbies harassing drivers for the GrabCar and Uber apps, which remain illegal in Thailand, the Department of Land Transport (DLT) has warned official taxi drivers not to threaten or confront suspected drivers for these services but to contact authorities to prosecute the drivers.

Cabbies have repeatedly harassed drivers—and those they suspect to be drivers for the services—yelling at them, surrounding them, and bullying them because they feel these drivers are stealing their customers.

However, Thais often complain that the traditional taxi drivers don’t want to pick them up or behave badly toward passengers and cite this as a reason the apps have become so popular.

A widely-shared cartoon from Thai Facebook page Contrast demonstrates one reason the apps have become so popular, because taxi drivers often tell you they don’t want to go to your destination.

The latest bullying report was of an incident at Chiang Mai Airport last week in which cabbies surrounded a Thai woman picking up a foreigner. They believed she was driving for one of the apps but, when officers questioned the woman later, they learned that the foreigner was simply a colleague she was providing a ride to, reported Bangkok Post.